The present invention relates generally to assemblies for controlling mechanical vibration and position. More particularly, it relates to shock absorbers of the type which use both an elastomeric shear spring and the flow of fluid through a restrictive valve for absorbing shock and dissipating energy in combination with apparatus and electronic logic control circuitry for controlling vibration of vibrating structures and vibrations caused elsewhere by vibrating structures, such as machinery.
The invention is particularly applicable as a mechanical coupler control system to be used for the support of items on naval vessels, particularly submarines, which are dependent upon not being acoustically detected at long ranges. However, it will be appreciated to those skilled in the art that the invention can be readily adapted for use in other environments as, for example, where similar vibration and position controlling mechanical coupler systems are employed to support or isolate other types of vibrating items.
The primary acoustic detections of submarines are made on the low frequencies radiated by the submarine hull, since low frequencies are not subject to the absorption experienced by higher frequencies. These low frequencies are produced by the vibrations of various machinery being transmitted through their support mounts and then radiated by the hull. Reduction of the low frequency transmissibility of the machinery support mounts would consequently decrease the probability of detection of submarines.
Various forms and types of mechanical coupler system assemblies have heretofore been suggested and employed, all with varying degrees of success. It has been found that defects present in most prior mechanical coupling assemblies are such that the assemblies themselves are of limited practical value for application in a naval vessel such as a submarine.
One of the conventional vibration isolation schemes involves mounting the vibrating machinery to a spring which is in turn fastened to a support foundation. The characteristics of the spring are selected to effect an optimal compromise between static deflection and resonant frequency of the system. It is preferred that the static deflection be small to maintain the desired position of the machinery. This requires the spring to be stiff. It is also preferred that the resonant frequency be low, which requires the spring to be compliant. The compromise selected between these two opposing preferences hopefully results in an acceptable static deflection and a resonant frequency somewhat lower than the lowest frequency expected to be generated by the vibrating machinery.
Unfortunately, this compromise is often unsatisfactory in that the resonant frequency cannot be made low enough to effect the desired degree of transmission loss or in that the static deflection is more than can be tolerated.
The present invention contemplates a new and improved assembly which overcomes all of the above referred to problems and others to provide a mechanical coupler control system in which the static deflection and the dynamic compliance are separately selectable, in which the assembly is readily adaptable to a plurality of uses with vibrating items having a variety of dimensional characteristics and which provides improved dynamic coupling operation between a support platform and the vibrating item.